Magnetrons



H. SIXSMITH June 3, I958 MAGNETRON S Original Filed Feb. 14, .1952

2 Sheets-Sheet 1 ee/06M CS a mw wgfi ATTORNEY 5 E [EV/Ill IIIIIIIIIIIIA June 3, 1958 H. SIXSMITH 2,837,695

MAGNETRONS Original Filed Feb. 14, 1952 2 Sheets-Sheet 2 IN VENTOR ear/84% 0510mm, 5 BY 51,6-, ,-$w,;fi

ATTORNEY$ United States Patent Electric Valve Company Limited, London, England, a

British company Original application February 14, 1952, Serial No. 271,527, now Patent No. 2,774,914, dated December 18, 1956. 1956, Serial No. 618,646

Claims priority, application Great Britain February 19, 1951 16 Claims. (Cl. SIS-39.67)

This invention relates to magnetrons and has for its object to provide improved magnetrons of high etficiency, simple construction and capable of delivering high powers at very high frequencies.

i This application is a division of my application Serial Number 271,527, filed February 14, 1952 for Magnetrons, now Patent 2,774,914, dated December 18, 1956.

According to this invention a magnetron comprises a hollow cavity resonator within which is at least one cathode and at least two anodes in such mutual relationship as to constitute a split anode magnetron system, said system being so positioned and arranged with respect to said cavity resonator that, when in operation, it excites a standing wave therein and said cavity resonator being provided with means for the withdrawal of useful power therefrom.

I The means for the withdrawal of useful power may take any of a variety of forms, for example, a loop inserted in the cavity resonator or a concentric line or wave guide output circuit.

, The invention is illustrated in the accompanying drawings in which Figure 1 is a schematic sectional elevation and Fig. 2 is a schematic end view of one embodiment. Figs. 3 to 8 inclusive are schematic views like Fig. 2, of ftnther embodiments.

In the form of construction shown in Figs. 1 and 2 there is provided, off-set within a cylindrical cavity resonator 1, an electrodesystem consisting of a rectilinear cathode 2 axially within two similar anodes 3 each shaped like a segment of a cylinder, with lineally extending spaced edges. The cathode 2 is parallel to and spaced a desired distance from the axis of the cylinder 1 and the split anode magnetron system consisting of the said cathode 2 and the anodes 3 extends over the greater part of the length of the cavity. The magnetic field may be provided by a coil 4 surrounding the cavity resonator 1 of non-magnetic material and supplied with current from a suitable D. C. source, indicated at 5. For the supply of D. C. operating voltage, the side 6 of the cathode may be connected to the negative of the high tension supply, indicated at 7, and the positive side connected to ground 9 to which also the resonator 1 is connected as indicated a at 10. The whole arrangement is such that operation of the said split anode system as in the normal way excites an H standing wave in the cavity resonator. This is indicated conventionally in broken lines in Fig. 2. Output energy is taken 011 from the cavity resonator in any manner known per sesuch as through the coupling means shown at 33.

Fig. 3 shows a modification suitable for use where higher power outputs are required. In Fig. 3 there is a ring of similar cathode and double anode systems each as above described. As shown the cathodes 2 are all parallel to one another and to the axis of the cavity resonator 1 and are equally spaced along an imaginary Divided and this application October 26,

2 ring having the cavity resonator axis as a center. Each cathode 2 is located within two anodes 3 just as in Figs. 1 and 2 with the lineal edges of the semicylindrical parts or members of anodes 3 spaced on opposite side of diametrical lines through the cavity resonator 1.

In a preferred and simpler construction shown in Fig. 4 and suitable for use on frequencies of the order of 30,000 mc./ s. or more, the segmental anodes 3 of the embodiment of Fig. 2 are replaced by rods 31 running parallel to the cathodes 2, each rod serving as a' common anode to two adjacent split anode magnetron systems consisting of two cathodes 2 and the common anode rod 31. Thus, as shown in Fig. 4 there may be as many rods 31 as there are cathodes 2, the rods alternating with the cathodes along, and at right angles to, an imaginary ring the axis of which is constituted by the axis of the cavity 1, each rod 31 being mid-way between two cathodes 2 and each cathode being mid-way between two rods 31. v

In a further modification of the arrangement of Fig. 4 shown in Fig. 5 the cathodes 2 and rod-anodes 31 are spaced at equal intervals along and at right angles to,

concentric rings having the axis of the cavity resonator 1 as a center, the cathodes 2 being in one ring, for example,

the outer one, and the rods 31 in the other, and the radii tobetween each anode and cathode with respect to the high frequency field should not be of major importance so that precise electrode location in this respect should not be a requirement. The anodes may, however, have secondary effects by introducing local disturbances of the high frequency field in their immediate neighborhoods but these disturbances may be expected to have favorable influences on electron motion in the constructions described.

In a further modification shown in Fig. 6 the anodes 31 and cathodes 2 are again in separate concentric rings and equally spaced along them but each anode is on a common radius with a cathode instead of being between two of them as in Fig. 5.

In still further modifications three concentric rings of electrodes are used, an intermediate ring of equally spaced cathodes 2 being arranged mid-way between two other rings of equally spaced anode rods 31, the said anode rods being either midway between the radii on which the cathodes lie as shown in Fig. 7 or on the same radii, not illustrated.

The multiple rod anode embodiments above described and illustrated may be modified as typified in Fig. 8 by replacing each adjacent pair of anode rods situated on the same circle by a segmental anode 32 lying on the said circle, opposite ends of each segment being, in operation,

at potentials of opopsite simultaneous sign and adjacent ends of adjacent segments being also at potentials of opposite simultaneous sign. This is conventionally indicated in Fig. 8 by plus and minus signs against a few, of

the anodes. In the construction of this nature shown in Fig. 8 there'is a ring of segmental anodes 32 lying in a arrangement may be regarded as operating in a mode corresponding to the zero mode of a conventional multicavity magnetron, the electrqns moving from one anodecathode region to the next in. approximately one oscillation of the cavity-resonator. This is conventionally indicated in broken lines at-the top of Fig. 8.

The cathodes and anodes employed in embodiments of this invention may be supported in any convenient way by means which, forreas'ons of simplification, are not shown in the drawings, for example, the anodes may be directly attached to the ends of the cavity 1 and the cathodes may be attached by means of extensions passing through holes in the ends of the cavity resonator to external supporting structures. Necessary cathode insulation, means for providing hermetic sealing and output circuit means for taking off the generating high frequency power are provided in any convenient man ner and may be conventional.

, While I have described my invention in certain preferred embodiments, I realize that modifications may be made, and I desire that it be understood that no limitations upon my invention are intended other than may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. A magnetron comprising a hollow cavity resonator, means for exciting a standing wave in said cavity resonator, comprising a plurality of concentrically arranged cathodes and rod-like anodes to constitute a plurality of magnetron systems mounted within said cavity resonator, means for providing a magnetic field within said resonator, power supply means for said systems, and means for effecting the withdrawal of useful power from said cavity resonator.

2. A magnetron as set forth in claim 1 wherein said hollow cavity resonator is cylindrical in shape and wherein saidcathodes and rod-like anodes comprise electrodes that are alternately spaced in a ring, said cathodes being from said equally spaced rod-like anodes, all said electrodes extending on axes parallel to the cavity resonator axis and being spaced therefrom.

3. A magnetron as set forth in claim 1 wherein said hollow cavity resonator is cylindrical in shape and wherein said cathodes and rod-like anodes constitute electrodes that are, arranged within said cavity resonator, said electrodes consisting of a ring of equally spaced cathodes.

and a concentric ring of equally spaced rod-like anodes, all said electrodes extending on axes parallel to and spaced from the cavity resonator axis.

4-. A magnetron as set forth in claim 1 wherein said hollow cavity resonator is cylindrical in shape and wherein said cathode and rod-like anodes constitute electrodes that are arranged within said cavity resonator, said electrodes consisting of a ring of equally spaced cathodes and a concentric ring of equally spaced rod-like anodes, all said electrodes extending on axes that are parallel to and spaced from the cavity resonator axis, each anode being disposed on a common cavity resonator radius with one of the cathodes.

-5. A magnetron as set forth in claim 1 wherein said hollow cavity resonator is cylindrical in shape and wherein said cathodes and rod-like anodes constitute electrodes that are concentrically arranged within said cavity resonator, said electrodes consisting of a ring of equally spaced cathodes and a concentric ring of equally spaced rod-like anodes, all said electrodes extending on axes that are parallel to and spaced from the cavity resonator axis, each anode being on a cavity resonator radius which is midway between the cavity resonator radii to two adjacent cathodes.

6. A magnetron as set forth in claim 1 wherein said hollow cavity resonator is cylindrical in shape and wherein said cathodes are rod-like anodes constitute electrodes that are concentrically arranged within said cavity resonator, said electrodes consisting of a ring of equally 4 spaced cathodes and two concentric rings of equally spaced rod-like anodes, the first of said three rings being disposed midway between the other two and each anode in the outermost ring being on a common cavity resonator radius with an anode in the innermost ring, all the electrodes extending on axes parallel to the cavity resonator axis and spaced therefrom.

7. A magnetron as set forth in claim 1 wherein said hollow cavity resonator is cylindrical in shape and wherein said cathodes and rod-like anodes constitute electrodes that are concentrically arranged within said cavity resonator,.said electrodes consisting of a ring of equally spaced cathodes and two concentric rings of equally spaced rod-like anodes, the first of said three rings being disposed midway between the other two and each anode in the outermost ring being on a common cavity resonator radius with an anode in the innermost ring, all the electrodes extending on axes parallel to the cavity resonator axis and spaced therefrom, each cathode being disposed on a common cavity resonator radius with two anodes.

8. A magnetron as set forth in claim 1 wherein said hollow cavity resonator is cylindrical in shape and wherein said cathodes and rod-like anodes constitute electrodes that are concentrically arranged within said cavity resonator, said electrodes consisting of a ring of equally spaced cathodes and two concentric rings of equally spaced rods, the first of said three rings being midway between the other two and each anode in the outermost ring being on a common cavity resonator radius with an anode in the innermost ring, all the electrodes extending parallel to the cavity resonator axis andspaced therefrom, each cathode being disposed midway between the cavity resonator radii to two adjacent anodes in a ring.

9. A magnetron as set forth in claim 1 wherein the hollow cavity resonator is cylindrical in shape and where said cathodes and rod-like anodes constitute electrodes that are concentrically arranged within said cavity resonator, said electrodes consisting of a ring of equally spaces cathodes and a concentric ring of equally spaced rod-like anodes, all said electrodes having individual axes extending parallel to the cavity resonator axis and spaced therefrom, said rod-like anodes being located on equal 'radii extending from the center of said hollow cavity resonator.

10. A magnetron as set forth in claim 1 wherein the adjacent rod-like anodesof adjacent magnetron systems are equally spaced along a first imaginary ring and wherein the cathodes are equally spaced along a second imaginary ring, both of said rings having the cavity resonator axis as a center.

11. A magnetron as set forth in claim 1 wherein the adjacent rod-like anodes of adjacent magnetron systems are equally spaced along a first imaginary ring and wherein the cathodes are equally spaced along a second imaginary ring, both of said rings having the cavity resonator axis as a center, and wherein imaginary lines connecting a cath- :ode with its two adjacent rod-like anodes form an isosceles triangle.

12. A magnetron as set forth in claim 1 wherein the adjacent rod-like anodes of adjacent magnetron systems are equally spaced along a first imaginary ring and wherein the cathodes are equally spaced along a second imaginary ring, both of said rings having the cavity reso nator axis as a center and wherein extra rods are provided, one rod of the total number of rods being situated on each cavity resonator radius that passes through a cathode.

13. A magnetron as set forth in claim 1 wherein the adjacent rod-like anodes of adjacent magnetron systems are equally spaced along a first imaginary ring and wherein the cathodes are equally spaced along a second imaginary ring, both of said rings having the cavity resonator axis as a center, and wherein extra rods are provided, said extra rods being equally spaced along a third imaginary ring having the :cavity resonator axis as a center, the second imaginary ring being midway between the first and third imaginary rings and each rod on said first imaginary ring being on a common cavity resonator radius with a rod on said third imaginary ring.

14. A magnetron as set forth in claim 1 wherein the adjacent rod-like anodes of adjacent magnetron systems are equally spaced along a first imaginary ring wherein the cathodes are equally spaced along a secondary ring, both of said rings having the cavity resonator axis as a center, where extra rods are provided, said extra rods being equally spaced along a third imaginary ring having the cavity resonator axis as a center, the second imaginary ring being disposed midway between the first and third imaginary rings and each rod on said first imaginary ring being on a [common cavity resonator radius with a rod on said third imaginary ring, and wherein each cathode is on a common cavity resonator radius with two rods.

\ 15. A magnetron as set forth in claim 1 wherein the adjacent rod-like anodes of adjacent magnetron systems are equally spaced along a first imaginary ring wherein the cathodes are equally spaced along a second imaginary ring, both of said rings having the cavity resonator axis as a center, wherein extra rods are provided, said extra rods being equally spaced along a third imaginary ring having the cavity resonator axis as a center, the second imaginary ring being midway between the first and third imaginary rings and each rod on said first imaginary ring being midway on a common cavity resonator radius with a rod on said third imaginary ring, and wherein each cathode is situated on the bisector of the angle subtended by the cavity resonator radii passing through two adjacent rods on a ring.

16. A magnetron as set forth in claim 1, wherein the adjacent rod-like anodes of adjacent magnetron systems are equally spaced, on one imaginary ring, and the cathodes being arranged, equally spaced, on another imaginary ring, both of said rings having the cavity resonator axis as a center, the opposite ends of each anode being, in operation, at potentials of opposite simultaneous sign and adjacent ends of adjacent rods being also at potentials of opposite simultaneous sign.

References Cited in the file of this patent UNITED STATES PATENTS 

